I don't have the newer 2.8L II. Wish I did. Before buying this, lens I looked at Canon's MTF charts and realized it wasn't a super sharp lens. However, there are times when I just need a very wide angle in conjunction with full frame sensor.

I'm not a fan of fisheyes, especially for architecture so I conciously made the decision to accept a lens that was soft. The 4 stars are awarded because I knew what I was getting before I purchased.

If you don't know how to read Canon's MTF charts, seach their site for the majic decoder ring. Those charts can make or break a decision so you aren't surprised.